aroundAll hook

[srghma]

related hspec/hspec#255

[srghma]

module Lib.AroundAll where

import Prelude (Unit, bind, discard, pure, void, ($), (<<<))

import Effect.Aff (Aff, Error, Fiber, forkAff, killFiber)
import Effect.Aff.Class (class MonadAff, liftAff)
import Effect.Class (class MonadEffect)
import Effect.Exception as Effect.Exception
import Effect.Aff.AVar as Effect.Aff.AVar
import Control.Monad.Error.Class (class MonadError)
import Data.Tuple (Tuple(..), fst)
import Test.Spec (SpecT, afterAll, beforeAll, beforeWith)

-- | Run a custom action before first and after last spec item.

-- | Example usage - to make a database provider for a group of tests

-- it's possible to make `withFunc` argument to have type
--
-- ((config -> g Unit) -> g Unit)
--
-- instead of
--
-- ((config -> g Unit) -> Aff Unit)
--
-- but it would require g to implement `MonadUnliftAff` class (there should be function `g Unit -> Aff Unit`)

aroundAll :: forall config m g . MonadEffect m => MonadAff g => MonadError Error g => ((config -> g Unit) -> Aff Unit) -> SpecT g config m Unit -> SpecT g Unit m Unit
aroundAll withFunc specWith = beforeAll start $ afterAll stop $ beforeWith (pure <<< fst) specWith
  where
        start :: g (Tuple config (Fiber Unit))
        start = do
           (avar :: Effect.Aff.AVar.AVar config) <- liftAff $ Effect.Aff.AVar.empty -- 1

           fiber <- liftAff $ forkAff $ withFunc $ \value -> do
              liftAff $ Effect.Aff.AVar.put value avar -- 2
              liftAff $ void $ Effect.Aff.AVar.take avar -- 3

           theConfig <- liftAff $ Effect.Aff.AVar.take avar -- 2

           pure (Tuple theConfig fiber)

        stop :: Tuple config (Fiber Unit) -> g Unit
        stop (Tuple _config fiber) = liftAff $ killFiber (Effect.Exception.error "Kill fiber") fiber